The invention relates to semiconductor processing equipment and more particularly to a ceramic liner for a processing chamber such as a plasma etching chamber.
In the field of semiconductor processing, vacuum processing chambers are generally used for etching and chemical vapor deposition (CVD) of materials on substrates by supplying an etching or deposition gas to the vacuum chamber and application of an RF field to the gas to energize the gas into a plasma state. Examples of parallel plate, transformer coupled plasma (TCP(trademark)) which is also called inductively coupled plasma (ICP), and electron-cyclotron resonance (ECR) reactors and components thereof are disclosed in commonly owned U.S. Pat. Nos. 4,340,462; 4,948,458; 5,200,232 and 5,820,723. Because of the corrosive nature of the plasma environment in such reactors and the requirement for minimizing particle and/or heavy metal contamination, it is highly desirable for the components of such equipment to exhibit high corrosion resistance.
During processing of semiconductor substrates, the substrates are typically held in place within the vacuum chamber on substrate holders by mechanical clamps and electrostatic clamps (ESC). Examples of such clamping systems and components thereof can be found in commonly owned U.S. Pat. Nos. 5,262,029 and 5,838,529. Process gas can be supplied to the chamber in various ways such as by gas nozzles, gas rings, gas distribution plates, etc. An example of a temperature controlled gas distribution plate for an inductively coupled plasma reactor and components thereof can be found in commonly owned U.S. Pat. No. 5,863,376.
Aluminum and aluminum alloys are commonly used for walls of plasma reactors. In order to prevent corrosion of the walls, various techniques have been proposed for coating the aluminum surface with various coatings. For instance, U.S. Pat. No. 5,641,375 discloses that aluminum chamber walls have been anodized to reduce plasma erosion and wear of the walls. The ""375 patent states that eventually the anodized layer is sputtered or etched off and the chamber must be replaced. U.S. Pat. No. 5,680,013 states that a technique for flame spraying Al2O3 on metal surfaces of an etching chamber is disclosed in U.S. Pat. No. 4,491,496. The ""013 patent states that the differences in thermal expansion coefficients between aluminum and ceramic coatings such as aluminum oxide leads to cracking of the coatings due to thermal cycling and eventual failure of the coatings in corrosive environments. U.S. Pat. No. 5,085,727 discloses a carbon coating for walls of a plasma chamber wherein the coating is deposited by plasma assisted CVD.
In order to protect the chamber walls, U.S. Pat. Nos. 5,366,585; 5,556,501; 5,788,799; 5,798,016; and 5,885,356 propose liner arrangements. For instance, the ""585 patent discloses a free standing ceramic liner having a thickness of at least 0.005 inches and machined from solid alumina. The ""585 patent also mentions use of ceramic layers which are deposited without consuming the underlying aluminum can be provided by flame sprayed or plasma sprayed aluminum oxide. The ""501 patent discloses a process-compatible liner of polymer or quartz or ceramic. The ""799 patent discloses a temperature controlled ceramic liner having a resistance heater embedded therein and the ceramic can be alumina, silica, titania, zirconia, silicon carbide, titanium carbide, zirconium carbide, aluminum nitride, boron nitride, silicon nitride and titanium nitride. The ""016 patent discloses a liner of ceramics, aluminum, steel and/or quartz with aluminum being preferred for its ease of machinability and having a coating of aluminum oxide, Sc2O3 or Y2O3, with Al2O3 being preferred for coating aluminum to provide protection of the aluminum from plasma. The ""356 patent discloses a ceramic liner of alumina and a ceramic shield of aluminum nitride for the wafer pedestal for use in CVD chambers. U.S. Pat. No. 5,904,778 discloses a SiC CVD coating on free standing SiC for use as a chamber wall, chamber roof, or collar around the wafer. U.S. Pat. No. 5,292,399 discloses a SiC ring surrounding a wafer pedestal. A technique for preparing sintered SiC is disclosed in U.S. Pat. No. 5,182,059.
With regard to plasma reactor components such as showerhead gas distribution systems, various proposals have been made with respect to the materials of the showerheads. For instance, commonly owned U.S. Pat. No. 5,569,356 discloses a showerhead of silicon, graphite, or silicon carbide. U.S. Pat. No. 5,888,907 discloses a showerhead electrode of amorphous carbon, SiC or Al. U.S. Pat. Nos. 5,006,220 and 5,022,979 disclose a showerhead electrode either made entirely of SiC or a base of carbon coated with SiC deposited by CVD to provide a surface layer of highly pure SiC.
In view of the need for high purity and corrosion resistance for components of semiconductor processing equipment, there is a need in the art for improvements in materials and/or coatings used for such components. Moreover, with regard to the chamber materials, any materials which can increase the service life of a plasma reactor chamber and thus reduce the down time of the apparatus, would be beneficial in reducing the cost of processing the semiconductor wafers.
The invention provides a tiled liner for a plasma processing chamber wherein semiconductor substrates can be processed. The tiled liner comprises an assembly of ceramic tiles located inwardly of a sidewall of the chamber. The plasma chamber can include a substrate support, a gas supply and an energy source. The substrate support on which one or more substrates can be processed is located within the interior space of the chamber. The chamber sidewall is spaced outwardly of a periphery of the substrate support and the gas supply supplies process gas to the interior space. The energy source energizes the process gas in the interior space into a plasma state during processing of the substrate.
According to a preferred embodiment, the tiled liner is supported by a resilient support member such as an elastomeric joint or an elastically bendable metal frame. For instance, the resilient support can comprise an elastomeric joint which attaches each of the ceramic tiles to a respective metal backing member. The metal backing members can be supported on an elastically bendable metal frame supported by a thermally controlled member such that heat can be withdrawn from the ceramic tiles via a thermal path which extends through the elastomeric joint, the metal backing members and the bendable metal frame to the thermally controlled member. Alternatively, the resilient support can comprise an elastomeric joint between each of the ceramic tiles and the chamber sidewall.
The tiles can be a series of interlocked ceramic tiles such as SiC tiles. The elastically bendable metal frame can include an inner frame member and an outer frame member, the inner frame member being supported by the outer frame member and the outer frame member being supported by the chamber. The inner and outer metal frame members can be configured to allow differential thermal stresses on the tiled liner and the frame members to be accommodated during operation of the plasma processing system. In such an arrangement, an upper portion of the outer frame member can be supported by a thermally controlled part of the chamber, a lower portion of the outer frame member can be attached to a lower portion of the inner frame member, and the tiled liner can be supported by the inner frame member. Further, the bendable metal frame can include a continuous upper portion and a segmented lower portion. For instance, the bendable metal frame can be cylindrical and the segmented lower portion can comprise axially extending segments separated from each other by axially extending slots. If the inner and outer metal frame members are cylindrical and include continuous upper portions and segmented lower portions, the segmented lower portions comprise axially extending segments separated from each other by axially extending slots.
According to another embodiment of the invention, a ceramic plasma screen extends inwardly from a lower portion of the tiled liner, the ceramic plasma screen including passages through which process gas and reaction byproducts are removed from the interior of the chamber during processing of a substrate. For instance, the ceramic plasma screen can comprise a plurality of discrete screen segments supported in an annular space between the chamber sidewall and the substrate support, the passages comprising slots extending radially inwardly from the chamber sidewall. The ceramic plasma screen can be attached to the bendable metal frame by an electrically conductive elastomeric joint and the plasma screen can be electrically grounded to the bendable metal frame by the elastomeric joint.